Non-contact power feeding technologies by which electric power is contactlessly supplied without using a power cord are attracting attention. Current wireless power feeding technologies are broadly classified into three types: (A) a type in which electromagnetic induction is used (for a short distance), (B) a type in which radio waves are used (for a long distance), and (C) a type in which resonance phenomenon in a magnetic field is used (for a middle distance).
Type (C), in which resonance phenomenon is used, is a relatively new technology. With this technology, high power transmission efficiency can be achieved even at a middle distance of several meters. Therefore, an idea that a power receiving coil is embedded at the bottom of the vehicle of an electric vehicle and electric power is contactlessly transmitted from a power feeding coil under the ground, for example, is under study.
An electric vehicle, which obtains electric power from a vehicle-mounted battery to travel, needs to be periodically charged, so it has been a practice that electric vehicles are parked at a place where a charger is placed and are charged by mutually connecting the battery and the charger with a connector. When a connector is used for charging, however, it is pointed out that workability concerning the handling of the connector and electric wire is poor. Therefore, there has been an increasing desire for a non-contact power feeding technology by which electric power is contactlessly supplied to a vehicle.
As indicated, for example, in PTL 1, a vehicle charging apparatus is disclosed by which an electromagnetic coil for receiving electric power (power receiving coil) attached to a vehicle and an electromagnetic coil for transmitting electric power (power feeding coil) provided in a car stop face each other with tires of the vehicle brought into contact with the car stop so that they can be electromagnetically coupled.